JP3695046B2 - Engine fuel injection method and apparatus - Google Patents

Description

（３）次に、噴射実行フラグ（詳細については、後述する）のＯＮ／ＯＦＦが判断され、噴射実行フラグがＯＦＦの場合には、ルーチン４１０へ移行し、噴射実行フラグがＯＮの場合には、ルーチン４２０へ移行する（Ｓ４０３）。ただし、初回は、ルーチン４１０へ移行する。
（４）ルーチン４１０では、コモンレール圧力Ｐｃの微分値Ｒと所定のスライスレベル（噴射実行判定値）Ｒｌとの大小が比較される（Ｓ４１１）。ＲがＲｌ以下である、即ち、噴射の実行がなされておらず且つコモンレール圧力Ｐｃの変化率が小であるときには噴射の開始もされていないと判断され、スタートに戻って、そのままコモンレール圧力Ｐｃ（Ｔ_n ）の検出が続行される。
（５）以上を繰り返すうちに、実際の噴射が開始されて、コモンレール圧力Ｐｃの微分値Ｒが噴射実行判定値Ｒｌを超えると、噴射フラグがＯＮとされ（Ｓ４１２）、その時の時刻Ｔｉｓが、噴射開始時刻としてメモリに記憶される（Ｓ４１３）。
（６）再度スタートに戻り、Ｓ４０１及びＳ４０２を実行すると、噴射フラグがＯＮになっているから、Ｓ４０３ではルーチン４２０へ移行する。
（７）ルーチン４２０では、再びコモンレール圧力Ｐｃの微分値Ｒが噴射実行判定値Ｒｌと比較され（Ｓ４２１）、噴射実行判定値Ｒｌを超えている間は、そのままスタートに戻り、コモンレール圧力Ｐｃ（Ｔ_n ）の検出を続行する。
（８）やがて、実際の噴射が終了して、コモンレール圧力Ｐｃの微分値Ｒが噴射実行判定値Ｒｌ以下になると、コモンレール圧力Ｐｃの変化が殆どないこと、即ち、燃料噴射が終了したことを意味するから、Ｓ４２１での判断を経て、噴射フラグがＯＦＦとされ（Ｓ４２２）、その時の時刻Ｔｉｅが噴射終了時刻としてメモリに記憶される（Ｓ４２３）。
（９）噴射開始時刻Ｔｉｓから噴射終了時刻Ｔｉｅまでの時間について、コモンレール圧力Ｐｃの微分値Ｒを積分して実行された総噴射量Ｑｔを求めて、メモリに記憶する（Ｓ４２４）。
（１０）また、噴射開始時刻Ｔｉｓから始まる初期噴射期間ｔｅ（即ち、着火遅れ期間）にわたってコモンレール圧力Ｐｃの微分値Ｒを積分して実行された初期噴射量Ｑｅを求めて、メモリに記憶する（Ｓ４２５）。
（１１）コモンレール圧力Ｐｃの微分値Ｒの最大値（例えば、最大値の近傍における複数点での微分値Ｒの平均値）を最大噴射率Ｒｍａｘとして、メモリに記憶する（Ｓ４２６）。
【００６２】
最後に、フィードバック補正量の演算について、図１０に示された「フィードバック補正量の演算ルーチン」に基づいて説明する。燃料ポンプの制御ルーチンとインジェクタの制御ルーチンの実行で求められた各目標噴射特性と、噴射率の計測ルーチンで測定された各実行された噴射特性とから、各基本目標制御量の補正量を求める。各補正量は、目標噴射特性と前回実行された噴射特性との偏差に対応した所定の関数として演算される。
【００６３】
まず、フィードバック補正量ＰＴｉｃルーチン５１０において、インジェクタ１の電磁弁２６へのコマンドパルス出力時期のフィードバック補正量が、コマンドパルス出力時期の制御上、目標噴射特性としての目標噴射時期Ｔｉｆと計測された実際の噴射特性としての噴射開始時刻Ｔｉｓとから求められる。即ち、実際の噴射開始時刻はＴｉｓであるから、当該インジェクタについての目標噴射時期Ｔｉｆと噴射開始時刻Ｔｉｓとが読み込まれ（Ｓ５１１）、両者の偏差（Ｔｉｆ−Ｔｉｓ）についての関数Ｕにより、フィードバック補正量ＰＴｉｃが求められる（Ｓ５１２）。求められたフィードバック補正量ＰＴｉｃは、図６に示す電磁弁に対する最終目標コマンドパルス出力時期の設定ルーチンにおいて読み込まれて（Ｓ３１３）、Ｓ３１２で設定された基本目標コマンドパルス出力時期ＰＴｉｂに加算され、インジェクタ１の電磁弁２６への最終目標コマンドパルス出力時期ＰＴｉｆが、最終目標制御量として設定される（Ｓ３１４）。
【００６４】
次に、フィードバック補正量ＰＷｉｔｃルーチン５２０において、インジェクタ１の電磁弁２６への総コマンドパルス幅のフィードバック補正量が、総コマンドパルス幅の制御上、目標噴射特性としての最終目標総噴射量Ｑｔｆと計測された実際の噴射特性としての総噴射量Ｑｔとから求められる。即ち、実際の総噴射量はＱｔであるから、当該インジェクタについての最終目標総噴射量Ｑｔｆと総噴射量Ｑｔとが読み込まれ（Ｓ５２１）、両者の偏差（Ｑｔｆ−Ｑｔ）についての関数Ｖにより、フィードバック補正量ＰＷｉｔｃが求められる（Ｓ５２２）。求められたフィードバック補正量ＰＷｉｔｃは、図７に示す電磁弁に対する最終目標総コマンドパルス幅の設定ルーチンにおいて読み込まれて（Ｓ３２２）、Ｓ３２１で設定された基本目標総コマンドパルス幅ＰＷｉｔｂに加算され、インジェクタ１の電磁弁２６への最終目標総コマンドパルス幅ＰＷｉｔｆが、最終目標制御量として設定される（Ｓ３２３）。
【００６５】
次に、フィードバック補正量ＰＷｉｅｃ５３０において、インジェクタ１の電磁弁２６への初期コマンドパルス幅のフィードバック補正量が、初期コマンドパルス幅の制御上、目標噴射特性としての目標初期噴射量Ｑｅｆと計測された実際の噴射特性としての初期噴射量Ｑｅとから求められる。即ち、実際の初期噴射量はＱｅであるから、当該インジェクタについての目標初期噴射量Ｑｅｆと初期噴射量Ｑｅとが読み込まれ（Ｓ５３１）、両者の偏差（Ｑｅｆ−Ｑｅ）についての関数Ｙにより、フィードバック補正量ＰＷｉｅｃが求められる（Ｓ５３２）。求められたフィードバック補正量ＰＷｉｅｃは、図８に示す電磁弁に対する最終目標初期コマンドパルス幅の設定ルーチンにおいて読み込まれ（Ｓ３３３）て、Ｓ３３２で設定された基本目標初期コマンドパルス幅ＰＷｉｅｂに加算され、インジェクタ１の電磁弁２６への最終目標初期コマンドパルス幅ＰＷｉｅｆが、最終目標制御量として設定される（Ｓ３３４）。
【００６６】
最後に、フィードバック補正量ＰＴｐｆルーチン５４０において、燃料ポンプ８の流量制御弁１５へのコマンドパルス出力時期のフィードバック補正量が、コマンドパルス出力時期の制御上、目標噴射特性としての目標最大噴射率Ｒｍａｘｂと計測された実際の噴射特性としての最大噴射率Ｒｍａｘとから求められる。即ち、実際の最大噴射率は図９に示すＳ４２６で求められるようにＲｍａｘであるから、当該インジェクタについての目標最大噴射率Ｒｍａｘｂと最大噴射率Ｒｍａｘとが読み込まれ（Ｓ５４１）、両者の偏差（Ｒｍａｘｂ−Ｒｍａｘ）についての関数Ｚにより、フィードバック補正量として、燃料ポンプへのコマンドパルス出力時期のフィードバック補正量ＰＴｐｃが求められる（Ｓ５４２）。求められたフィードバック補正量ＰＴｐｃは、図４に示す燃料ポンプの制御ルーチンにおいて読み込まれて（Ｓ２０６）、Ｓ２０５で設定された燃料ポンプに対する基本目標初期コマンドパルス出力時期ＰＴｐｂに加算され、燃料ポンプ８の流量制御弁１５への最終目標コマンドパルス出力時期ＰＴｐｆが、最終目標制御量として設定される（Ｓ２０７）。
【００６７】
次に、この発明によるエンジンの燃料噴射装置による制御の時間的経過を、図１１に基づいて時間の経過に沿って説明する。なお、既に、クランクシャフトの２回転前に第３気筒についての前回の燃料噴射制御が行われているとする。
（１）第１気筒に対して設けられた気筒判別信号ＣＹＬの出力パルスが検出されると、その立下がりに合わせて、第１気筒が上死点に到来したことを表す上死点信号ＴＤＣが出力される。そして、上死点信号ＴＤＣの立下がりに対応して、クランクシャフトに取り付けられた所定歯数（例えば、３６歯）のギヤプレートとピックアップセンサとからなるエンジン回転数センサ４０からのパルス信号の立下がりに対応して、コントローラ１２内のクロックＴ_n が計時を開始する（Ｔ_n ＝０）。また、エンジン回転数センサ４０からのパルス信号は、アクセルペダルの踏込み量Ａｃｃと共に常にコントローラ１２に入力されている。更に、コモンレール圧力ＰｃもクロックＴ_n に基づいて最終的にはデジタル値となるように検出されており、隣合うクロックＴ_n における変化率に比例する値として燃料噴射率が演算されている。第１気筒が上死点に到来したことを表す上死点信号ＴＤＣに基づいて、次に上死点に到来する第３気筒の燃料噴射が制御される。
【００６８】
（２）エンジン回転数Ｎｅとアクセル踏込み量Ａｃｃに基づいて２次元マップ目標噴射量データから今回の基本目標総噴射量Ｑｔｂが求められ、前回の基本目標総噴射量Ｑｐｔｂとの偏差に基づいて補正した今回の最終目標総噴射量Ｑｔｆが設定される。設定された最終目標総噴射量Ｑｔｆとエンジン回転数Ｎｅとに基づいて２次元マップ目標最大噴射率データから目標最大噴射率Ｒｍａｘｂが設定される。目標最大噴射率Ｒｍａｘｂを得るため、目標コモンレール圧力Ｐｃｆが設定され、現在のコモンレール圧力Ｐｃとの偏差に応じて燃料ポンプ８の吐出側に設けられる流量制御弁１５への基本目標コマンドパルス出力時期ＰＴｐｂが決定される。即ち、基本目標コマンドパルス出力時期ＰＴｐｂからプランジャストロークの終点までの間に、流量制御弁１５を通じて燃料ポンプ８からコモンレール２に燃料が送り込まれるので、その送り込み期間に応じてコモンレール圧力Ｐｃの大きさを制御することができる。基本目標コマンドパルス出力時期ＰＴｐｂが早いほど燃料噴射をすべきときのコモンレール圧力Ｐｃは大きくなる。
【００６９】
しかし、上記のような手法だけでは、燃料供給系の個々の部品のバラツキや経年変化に起因して目標最大噴射率Ｒｍａｘｂを正しく得ることができない。したがって、前回の燃料噴射の際のコモンレール圧力Ｐｃの微分（変化率）に基づく離散的な噴射率Ｒ（Ｔ_n ）から最大値を平均的に求めて、目標最大噴射率Ｒｍａｘｂと前回の同じ気筒による噴射率Ｒの最大値との偏差に応じたフィードバック補正量ＰＴｐｃを求めておき、今回の基本目標コマンドパルス出力時期ＰＴｐｂを上記フィードバック補正量ＰＴｐｃで補正した最終目標コマンドパルス出力時期ＰＴｐａｆを設定し、最終目標コマンドパルス出力時期ＰＴｐａｆにより、流量制御弁へのコマンドパルスを出力する。
【００７０】
（３）上記（２）で定めたように、コモンレール圧力が最大になった状態のときに、コントローラ１２からインジェクタ１の電磁弁２６に対して燃料噴射のコマンドが送られる。エンジン回転数Ｎｅと設定された最終目標総噴射量Ｑｔｆとが読み込まれ、コモンレール圧力Ｐｃが入力されると、最終目標総噴射量Ｑｔｆとエンジン回転数Ｎｅ又はコモンレール圧力Ｐｃとに基づいて、マップ等により、インジェクタ１の電磁弁２６に対する３つの噴射条件、即ち、基本目標コマンドパルス出力時期ＰＴｉｂ、基本目標総コマンドパルス幅ＰＷｉｔｆ、及び基本目標初期コマンドパルス幅ＰＷｉｅｆが、マップ等により求められる。コモンレール圧力Ｐｃが既に決定されているとすると、インジェクタ１による燃料噴射のこの３つの条件により、燃料噴射量及び燃料噴射率の制御をほぼ一義的に定めることができる。
【００７１】
しかし、上記のような手法だけでは、燃料供給系の個々の部品のバラツキや経年変化に起因して上記３つの量を正しく定めることができない。したがって、前回の噴射の際のコモンレール圧力Ｐｃを逐次微分しておき、この微分値に基づいて、当該気筒での今回の燃料噴射に際して上記３つの量を補正する。即ち、この微分値に基づいて、前回の噴射の際のコモンレール圧力Ｐｃが変化し始めた時期Ｔｉｓを実際に求め、Ｔｉｓと前回の噴射の際の目標噴射時期Ｔｉｆとの偏差に基づいて、コマンドパルス出力時期のフィードバック補正量ＰＴｉｃを求めておき、当該気筒での今回の噴射の際に、上記フィードバック補正量ＰＴｉｃでもって今回の噴射の基本目標コマンドパルス出力時期ＰＴｉｂを補正する。
【００７２】
また、基本目標総コマンドパルス幅ＰＷｉｔｆは燃料噴射量に大きく関係する量であるから、前回の噴射の際のコモンレール圧力Ｐｃの微分値を噴射期間（Ｔｉｅ−Ｔｉｓ）にわたって積分して得られた総噴射量Ｑｔと目標総噴射量Ｑｔｆとの偏差に基づいて、総コマンドパルス幅のフィードバック補正量ＰＷｉｔｃを求めておき、上記フィードバック補正量ＰＷｉｔｃでもって、今回の噴射の際の基本目標総コマンドパルス幅ＰＷｉｔｆを補正する。
【００７３】
更に、基本目標初期コマンドパルス幅ＰＷｉｅｆについても、前回の噴射の際のコモンレール圧力Ｐｃの微分値を初期噴射期間ｔｆにわたって積分して得られた初期噴射量Ｑｅと目標初期噴射量Ｑｅｆとの偏差に基づいて、初期コマンドパルス幅のフィードバック補正量ＰＷｉｅｃを求めておき、上記フィードバック補正量ＰＷｉｅｃでもって、今回の噴射の際の基本目標初期コマンドパルス幅ＰＷｉｅｆを補正する。
【００７４】
なお、コモンレール圧力Ｐｃを検出する圧力センサ１３からの信号は、Ａ／Ｄ変換器１６と、高速演算用素子であるＤＳＰ（Ｄｉｇｉｔａｌ ＳｉｇｎａｌＰｒｏｃｅｓｓｏｒ）１７とを経てコントローラ１２のＣＰＵに入力され、コントローラ１２の演算負担を軽減している。
【００７５】
【発明の効果】
この発明によるエンジンの燃料噴射装置は、上記のように、同じインジェクタについて、前回の燃料噴射の際のコモンレール圧力の微分値から得られる各種のデータに基づいて、燃料ポンプとコモンレールとを接続する燃料路に設けられている流量制御弁やインジェクタに設けられている電磁弁へのコマンドパルスについての今回の燃料噴射の諸量を補正することにより、インジェクタ等の燃料噴射を行う各構成部品の製造上及び組立上のバラツキや、経年変化を補正して、最良の状態で燃料噴射を実行することができ、燃焼のバラツキによる排気ガス中に、ＨＣ（ハイドロカーボン）や煤等の発生を抑え、且つエンジンの騒音や振動を低減することができる。
【図面の簡単な説明】
【図１】この発明によるエンジンの燃料噴射装置による、気筒の制御タイミングと順序を示すエンジン制御のメインルーチンを示す図である。
【図２】図１におけるフローの各気筒の制御ルーチンを示す図である。
【図３】図２における気筒制御のうち目標噴射量の設定ルーチンを示す図である。
【図４】図２における気筒制御のうち燃料ポンプの制御ルーチンを示す図である。
【図５】図２における気筒制御のうちインジェクタの制御ルーチンを示す図である。
【図６】図５に示すインジェクタの制御ルーチンのうち電磁弁に対する最終目標コマンドパルス出力時期の設定ルーチンを示す図である。
【図７】図５に示すインジェクタの制御ルーチンのうち電磁弁に対する最終目標総コマンドパルス幅の設定ルーチンを示す図である。
【図８】図５に示すインジェクタの制御ルーチンのうち電磁弁に対する最終目標初期コマンドパルス幅の設定ルーチンを示す図である。
【図９】図２における気筒制御のうち噴射率の計測ルーチンを示す図である。
【図１０】図４，図６，図７及び図８において読み込まれる各フィードバック補正量の演算ルーチンを示す図である。
【図１１】この発明によるエンジンの燃料噴射装置による各コマンド、コモンレール圧力及び噴射率についての経時的な変化を示すグラフである。
【図１２】従来のコモンレール式燃料噴射システムの概略図である。
【図１３】従来のコモンレール式燃料噴射システムに用いられるインジェクタの一例を示す断面図である。
【図１４】コモンレール式燃料噴射システムにおいて、コモンレール圧力をパラメータとしたインジェクタの燃料噴射量と電磁弁へのコマンドパルス幅との関係を示す特性線図である。
【図１５】コモンレール式燃料噴射システムにおいて、アクセルペダル踏込み量をパラメータとしたエンジン回転数と基本噴射量との関係を示す基本噴射量特性線図である。
【図１６】従来のコモンレール式燃料噴射装置によるインジェクタの燃料噴射率の時間経過を示すグラフである。
【符号の説明】
１ インジェクタ
２ コモンレール
３ 分岐管
７ 燃料管
８ 燃料ポンプ
９ 燃料管
１２ コントローラ
１３ 圧力センサ
１５ 流量制御弁
１７ ＤＳＰ
２５ 噴孔
２６ 電磁弁
４０ エンジン回転数センサ
４１ 気筒判別センサ
４２ 上死点センサ
４３ アクセルペダル踏込み量センサ
４４ 冷却水温センサ
４５ 大気温度センサ
４６ 大気圧センサ
４７ 吸気管内圧力センサ
Ｐｃ コモンレール圧力
Ｑｔ 総噴射量
Ｑｅ 初期噴射量
Ｑｔｆ 最終目標総噴射量
Ｑｔｅ 目標初期噴射量
Ｒｎａｘｂ 目標最大噴射率
Ｒｍａｘ 最大噴射率
Ｔｉｆ 目標噴射時期
Ｔｉｓ 噴射開始時期
ＰＴｐｂ 流量制御弁への基本目標コマンドパルス出力時期
ＰＴｐｃ ＰＴｐｂのフィードバック補正量
ＰＴｐｆ 流量制御弁への最終目標コマンドパルス出力時期
ＰＴｉｂ 電磁弁への基本目標コマンドパルス出力時期
ＰＴｉｃ ＰＴｉｂのフィードバック補正量
ＰＴｉｆ 電磁弁への最終目標コマンドパルス出力時期
ＰＷｉｔｂ 電磁弁への基本目標総コマンドパルス幅
ＰＷｉｔｃ ＰＷｉｔｂのフィードバック補正量
ＰＷｉｔｆ 電磁弁への最終目標総コマンドパルス幅
ＰＷｉｅｂ 電磁弁への基本目標初期コマンドパルス幅
ＰＷｉｅｃ ＰＷｉｅｂのフィードバック補正量
ＰＷｉｅｆ 電磁弁への最終目標初期コマンドパルス幅[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine fuel injection method and apparatus for injecting fuel stored in a common rail by an injector.
[0002]
[Prior art]
Regarding the fuel injection control of an engine, a common rail fuel injection system is known as a method of increasing the injection pressure and optimally controlling the injection conditions such as the fuel injection timing and the injection amount in accordance with the operating state of the engine. Yes. The common rail fuel injection system is a system that stores fuel pressurized to a predetermined pressure by a fuel pump, and injects the stored pressurized fuel into a combustion chamber corresponding to the injector under the control of a controller. . In the fuel flow path from the common rail to the injection hole of each injector through the branch pipe, a fuel pressure corresponding to the injection pressure is constantly acting. The controller controls each injector so that pressurized fuel is injected in each injector under optimal injection conditions for the operating state of the engine.
[0003]
An outline of the common rail fuel injection system will be described based on the example shown in FIG. In the common rail fuel injection system, fuel is supplied from a common rail 2 to a plurality of injectors 1 that inject fuel into each combustion chamber of the engine through a branch pipe 3 that constitutes a part of the fuel flow path. After passing through the filter 5 and the feed pump 6 from the fuel tank 4, the fuel is supplied through a fuel pipe 7 to a fuel pump 8 which is, for example, a plunger type variable displacement high pressure pump. The fuel pump 8 is driven by the engine, boosts the fuel to a required predetermined pressure, and supplies the fuel to the common rail 2 through the fuel pipe 9. The fuel pump 8 maintains the fuel pressure in the common rail 2 at a predetermined pressure. The fuel relieved from the fuel pump 8 is returned to the fuel tank 4 through the return pipe 10. Of the fuel supplied from the branch pipe 3 to the injector 1, the fuel that has not been spent on the injection into the combustion chamber is returned to the fuel tank 4 through the return pipe 11.
[0004]
The controller 12, which is an electronic control unit, includes an engine speed sensor 40 for detecting the engine speed Ne, an engine cylinder discrimination sensor 41, a top dead center (TDC) detection sensor 42, and an accelerator for detecting the accelerator pedal depression amount Acc. Pedal depression amount sensor 43, cooling water temperature sensor 44 for detecting cooling water temperature Tw, atmospheric temperature sensor 45 for detecting atmospheric temperature Ta, atmospheric pressure sensor 46 for detecting atmospheric pressure Pa, and intake pipe pressure Signals from various sensors for detecting the operating state of the engine such as the intake pipe pressure sensor 47 for detecting Pb are input. Based on these signals, the controller 12 controls the fuel injection conditions by the injector 1, that is, the fuel injection timing and the injection amount, so that the engine output becomes the optimum output in accordance with the operating state. The common rail 2 is provided with a pressure sensor 13, and a fuel pressure detection signal in the common rail 2 detected by the pressure sensor 13 is sent to the controller 12. When the fuel in the common rail 2 is consumed by the injector 1 injecting fuel, the fuel pressure in the common rail decreases, but the controller 12 controls the fuel pump 8 so that the fuel pressure in the common rail 2 becomes constant. To control the discharge pressure.
[0005]
FIG. 13 shows the structure of the injector 1 as a cross section. The injector 1 is attached in a sealed state to a hole provided in a base of a cylinder head or the like by a seal member, but the illustration of the structure of the cylinder head or the like is omitted. A branch pipe 3 is connected to the upper side portion of the injector 1 through a fuel inlet joint 20. Fuel passages 21 and 22 are formed inside the main body of the injector 1, and a fuel flow path is constituted by the branch pipe 3 and the fuel passages 21 and 22. The fuel supplied through the fuel flow path is injected into the combustion chamber from a nozzle hole 25 that opens when the needle valve 24 is lifted, through a passage around the fuel reservoir 23 and the needle valve 24.
[0006]
The injector 1 is provided with a balance chamber type needle valve lift mechanism for controlling the lift of the needle valve 24. That is, an electromagnetic valve 26 is provided at the top of the injector 1, and a control current as a control signal from the controller 12 is sent to the electromagnetic solenoid 28 of the electromagnetic valve 26 through the signal line 27. When the electromagnetic solenoid 28 is energized, the armature 29 rises and opens the on-off valve 32 provided at the end of the fuel passage 31, so that the fuel pressure of the fuel supplied from the fuel passage to the balance chamber 30 is the fuel. Released through path 31. A control piston 34 is provided in the hollow hole 33 formed in the main body of the injector 1 so as to be movable up and down. The control piston 34 is based on the fuel pressure acting on the tapered surface 36 facing the fuel reservoir 23 rather than the pushing force acting on the control piston 34 by the force based on the reduced pressure in the balance chamber 30 and the spring force of the return spring 35. Since the force to push up wins, the control piston 34 rises. As a result, the lift of the needle valve 24 is allowed, and fuel is injected from the injection hole 25. The fuel injection amount is determined by the fuel pressure in the fuel flow path and the lift of the needle valve 24 (lift amount, lift period). The lift of the needle valve 24 is controlled by the electromagnetic solenoid 28 for controlling the opening / closing of the opening / closing valve 32. Is determined by the injection pulse as a control current sent to.
[0007]
In general, FIG. 14 shows the relationship between the fuel injection amount Q of the injector 1 and the command pulse width W supplied from the controller 12 to the electromagnetic solenoid 28 using the fuel pressure Pc (fuel pressure in the common rail 2) as a parameter. . If the fuel pressure Pc is constant, the fuel injection amount Q increases as the command pulse width W increases, and the fuel injection amount Q increases as the fuel pressure Pc increases even at the same command pulse width W. Become. On the other hand, since the fuel injection is started or stopped with a certain time delay with respect to the rise time and fall time of the command pulse, the injection timing is controlled by controlling the timing when the command pulse is turned on or off. Is possible.
[0008]
The fuel injection amount for each combustion cycle is calculated based on the basic injection amount characteristic map shown in FIG. FIG. 15 shows the basic injection amount corresponding to the engine speed Ne when the horizontal axis is the engine speed Ne, the vertical axis is the basic injection amount Qtb, and the accelerator pedal depression amount Acc as a parameter is set to several values. The change of Qtb is shown. As can be seen from FIG. 15, when the accelerator pedal depression amount Acc is constant, the basic injection amount Qtb decreases as the engine speed Ne increases. Therefore, when the engine speed Ne increases for some reason, if the feedback is applied so as to decrease the fuel injection amount in accordance with the basic injection amount Qb, the engine speed Ne changes in a decreasing direction. The rotational speed is stabilized by the fuel injection amount when balancing with the internal resistance.
[0009]
In the engine fuel injection control device, the following proposals have been made as measures for accurately controlling the fuel injection timing and the fuel injection amount. That is, when the control is performed by controlling the reference time and the injection period from the reference time, in order to avoid the fuel injection amount from fluctuating greatly due to slight engine speed fluctuation, a dummy is provided separately from each cylinder of the engine. It has been proposed to detect the actual injection amount of the provided injector and use the detected value as data for determining the fuel injection amount (see Japanese Patent Application Laid-Open No. 62-182460).
[0010]
Further, the common rail pressure causes pulsation due to pumping of high-pressure fuel by the fuel supply pump, pressure drop at the time of injection, or water hammer effect by closing the valve at the end of injection, etc. It is empirically known that the pressure on the common rail at the falling edge of the command pulse is substantially equal to the actual injection pressure. Using this fact, it has been proposed to determine the fuel injection amount by sampling and detecting the pressure of the common rail at the time of falling (see Japanese Patent Laid-Open No. 5-125985).
[0011]
Furthermore, the command value of the injection pressure of the cylinder that performs the next injection is calculated based on the detected value of the operating state parameter such as the engine speed and the accelerator opening and the detected value of the injection pressure of the cylinder that has finished the previous injection. In the fuel injection control device for injecting fuel in the injection period corresponding to the injection pressure command value, when it is detected that the engine is in a transient state, the instantaneous injection pressure corresponding to the crank angle is determined for the fuel injection pressure. Common rail fuel injection that improves the accuracy of fuel injection control in the transient state by calculating the amount of change and correcting the injection pressure value used to determine the fuel injection period of the cylinder that will perform the next injection A control device has been proposed (see JP-A-6-93915).
[0012]
[Problems to be solved by the invention]
In the common rail type fuel injection control device described in each of the above publications, it is intended to improve the accuracy of fuel injection from the respective viewpoints, but taking into account variations in fuel injection among cylinders. is not. That is, in the common rail fuel injection system, the fuel injection rate injected from the injector depends on the common rail pressure, the nozzle injection hole diameter, the opening speed of the needle valve, the throttle of the fuel flow path, and the like. The common rail pressure is common to all injectors, but the nozzle hole diameter, needle valve opening speed, fuel flow restriction, and other factors are different for each injector. Even if the operating state of the solenoid valve used for the lift control is the same, variations in fuel injection rate characteristics such as fuel injection start timing, fuel injection rate, and maximum fuel injection pressure have occurred, making uniform control difficult It is said that.
[0013]
Variations occurring in each injector with respect to fuel injection will be specifically described based on the description of FIG. 16 showing the passage of time of the fuel injection rate. The graph of the fuel injection rate shown in FIG. 16 is the result of the fuel injection rate when the energization time to the solenoid valve of each injector is constant for the 6-cylinder engine. In the figure, the fuel injection rates of the two injectors having the greatest difference in the injection rates and the average value of the fuel injection rates of the six injectors are shown. There are three types of main factors that cause variations in the fuel injection rate of the injector, as described below. That is, as for the fuel injection start timing, as indicated by A in the figure, the crank angle CA varies within a range of 1.5 degrees, and the injection amount during the initial injection period (ignition delay period) tf is shown in the figure. As shown by B, there is a variation within a relative range of 30%. The maximum injection rate varies within a relatively 15% range as indicated by C in the figure.
[0014]
In this way, if the fuel injection characteristics of the injectors provided for each cylinder in one engine vary, optimal injection timing and injection amount cannot be obtained for each injector, and as a result, exhaust gas As a result, the cleanliness of the cylinder decreases, and the balance of combustion between the cylinders is lost, causing noise and vibration.
[0015]
The cause of this variation in fuel injection characteristics is that the nozzle nozzle hole diameter of the injector, the valve opening speed of the needle valve, the processing accuracy such as the size and roughness associated with the manufacture of components such as the throttle of the fuel flow path, and the assembly accuracy It is thought that there is variation. Since this variation is unique to each injector, it is necessary to further improve the accuracy of processing and assembling the components of the injector in order to suppress this variation uniformly. However, there is a problem that if the accuracy is improved, the manufacturing cost increases because the equipment is changed.
[0016]
Even if there are variations in the injection characteristics for each injector, if the variations can be detected and the injection characteristics corrected in the direction to eliminate the variations for each injector using the detected values, the cost of the equipment will increase. There is a problem that the injection characteristics can be uniformly controlled for all the injectors without further improving the machining accuracy and assembly accuracy of the parts constituting the injector until the update.
[0017]
[Means for Solving the Problems]
An object of the present invention is to solve the above-mentioned problem, and to detect the variation in the injection characteristic for each injector from the time differential of the pressure of the common rail by utilizing the fact that the fuel injection of each injector is electronically controlled. Thus, it is an object to provide a fuel injection control device for an engine that controls the timing and amount of fuel injection so that the injection characteristics for each injector are uniform.
[0018]
Among the variations in fuel injection characteristics, regarding the fuel injection start timing, the variation of the crank angle CA is suppressed to a range of 0.2 degrees, and the variation of the injection amount during the ignition delay period is relatively suppressed to a range of ± 5%. If the variation in the maximum injection rate can be kept within a relative range of ± 2%, the uniformity of combustion in each cylinder is satisfied, and the cleanliness of the exhaust gas is not reduced, and the mutual relationship between the cylinders is reduced. The balance of combustion is maintained, and noise and vibration are not deteriorated.
[0019]
  This inventionEngine fuel injection methodStores fuel delivered by a fuel pump in a common rail, injects the fuel supplied from the common rail through a fuel flow path into a combustion chamber of an engine from an injection hole formed in an injector, and changes the operating state of the engine. The target is detected by a sensor, the controller sets a target injection characteristic based on a detection signal from the sensor, and sets a basic target control amount corresponding to the target injection characteristic in order to execute the fuel injection by the injector. In the fuel injection method of the engine for controlling the injection characteristic by the injector based on the basic target control amount, the injection is based on a differential as a rate of change with time of fuel pressure in the common rail accompanying the fuel injection. The characteristic is calculated, and the variation in the injection characteristic of the injector is eliminated. Therefore, setting the final target control amount is corrected based on the basic target control amount and the injection characteristic and the target injection characteristic, and controls the injection characteristics by the injector based on the final target control amountThus, the injection characteristic includes at least a maximum injection rate calculated corresponding to the maximum value of the derivative of the fuel pressure, and an injection start time determined by a time when the derivative of the fuel pressure exceeds a predetermined value. A total injection amount obtained corresponding to an integral value obtained by integrating the derivative of the fuel pressure over a fuel injection period, or an initial injection obtained corresponding to an integral value obtained by integrating the derivative of the fuel pressure over an initial injection period. The target injection characteristic includes at least a target maximum injection rate, a target injection start timing, a target total injection amount, or a target initial injection amount.
[0020]
Since the fuel injection method for an engine according to the present invention has the above-described configuration, it operates as follows. That is, the injection characteristic of the injector is obtained based on the differential as the rate of change with time of the fuel pressure in the common rail accompanying the fuel injection. That is, information about the injection characteristics of the injector can be obtained by detecting the change of the fuel pressure of the common rail with the passage of time. The controller sets a target injection characteristic based on a detection signal from the sensor, and sets a basic target control amount corresponding to the target injection characteristic in order to execute fuel injection by the injector. By comparing this target injection characteristic with the injection characteristic obtained from the differential of the fuel pressure of the common rail, it is possible to know the degree of deviation from the target injection characteristic, that is, the degree of variation in the injection characteristic of each injector. it can. The final target control amount is set by correcting the basic target control amount in the fuel injection by the injector based on the information obtained by the comparison, and the injection characteristic by the injector is corrected and controlled based on the final target control amount.
[0021]
The main parameters that determine the injection characteristics of the injector are the injection timing of when to start the fuel injection, that is, the fuel injection start timing, the total injection amount of one injection that affects the engine output, and the influence on the main combustion is large It is the initial injection amount that is the injection amount during the initial injection period (ignition delay period), and the maximum injection rate that relates the total injection amount and the injection period. Therefore, in the fuel injection method of the engine, the injection characteristics include at least the following quantities. First, the maximum injection rate is obtained corresponding to the maximum value of the differential of the fuel pressure. The maximum value of the differential of the fuel pressure, except for positive and negative signs, means that the maximum drop in fuel pressure means that the maximum amount of fuel per unit time flows out of the common rail accordingly. Therefore, the maximum value of the differential fuel pressure corresponds to the maximum injection rate. In addition, the injection start time is obtained when the derivative of the fuel pressure exceeds a predetermined value. The fuel pressure drop exceeding a certain level means that the fuel has started to flow out of the common rail. Further, the total injection amount is obtained corresponding to an integral value obtained by integrating the derivative of the fuel pressure over the fuel injection period. The differential of the fuel pressure is the degree of decrease in the fuel pressure per unit time as described above, and means the ratio of the fuel flowing out from the common rail, that is, the fuel injection rate. Therefore, the integral is the injection amount. It is equivalent to. Further, the initial injection amount is obtained corresponding to an integral value obtained by integrating the derivative of the fuel pressure over the initial injection period. On the other hand, the target injection characteristic includes at least a target maximum injection rate, a target injection start timing, a target total injection amount, or a target initial injection amount of the fuel. These quantities can define important injection characteristics that have a significant impact on engine characteristics.
[0022]
In the engine fuel injection method, the differential of the fuel pressure in the common rail changes every moment and does not show a smooth change. Therefore, if the injection characteristic is controlled based on a specific differential value having a large instantaneous fluctuation, it may be difficult to obtain control that suppresses the originally intended variation. Is obtained as a smoothed characteristic curve, for example, a moving average value obtained by dividing a certain period of time.
[0023]
In the fuel injection method of the engine, the injection characteristic is a maximum injection rate, and the basic target control amount is output to a flow control valve provided in a fuel flow path connecting a fuel pump and a common rail. The basic target command pulse output timing calculated according to the target maximum injection rate in the basic target command pulse, and the final target control amount is determined so that the maximum injection rate is equal to the target maximum injection rate. This is the final target command pulse output timing with the output timing corrected.
[0024]
Although it is assumed that the common rail pressure itself fluctuates as described above, it can be said that the maximum injection rate generally depends on the level of fuel pressure in the common rail (hereinafter referred to as common rail pressure). Since the common rail pressure is determined by the amount of fuel discharged from the fuel pump, the fuel discharge period (for example, if the fuel pump is a plunger type fuel pump corresponds to the plunger stroke), the fuel discharge period to the common rail and the fuel tank It is possible to control the common rail pressure by allocating it to the leak period. That is, the target maximum injection rate is set by means of a map or the like obtained in advance from the injection amount to be injected this time and the engine speed, and the target common rail pressure is set and set corresponding to the maximum injection rate. Based on the deviation between the target common rail pressure and the current common rail pressure, the operation timing of the flow control valve, that is, the basic target command pulse output timing is set. However, there are variations in operation of individual flow control valves. Regardless of this variation, if the maximum value of the differential value of the common rail pressure is obtained, this value corresponds to the actual maximum injection rate, so it is based on a comparison between the actual maximum injection rate and the target maximum injection rate. The final target command pulse output timing is set by correcting the basic target command pulse output timing output to the flow control valve, the flow control valve so that the actual maximum injection rate matches the target maximum injection rate, That is, the common rail pressure is controlled.
[0025]
In the fuel injection method of the engine, the injection characteristic is an injection start time, and the basic target control amount is a basic target output to an electromagnetic valve provided in an injector for controlling opening and closing of the injection hole. The basic target command pulse output timing calculated according to the target injection start timing of the injector in the command pulse, and the final target control amount is the basic target command pulse output so that the injection start timing coincides with the target injection start timing. This is the final target command pulse output timing with the timing corrected.
[0026]
That is, regarding the fuel injection start timing by the injector, even if the current (command pulse) for exciting the solenoid of the solenoid valve of the injector is known, the opening / closing to release the pressure in the solenoid, armature, and balance chamber Response time delays such as the behavior of valves and needle valves are different for each injector. However, if the common rail pressure is detected, the time when the common rail pressure starts to drop is the actual injection start time regardless of the presence or absence of the variation. Therefore, the actual injection start timing is always known with respect to the target injection start timing. A basic target command pulse is output to the solenoid valve provided in the injector for controlling opening and closing of the nozzle hole for opening the valve, but the basic target command pulse output timing according to the target injection start timing of the injector Is calculated. The basic target command pulse output timing is sequentially corrected based on the comparison between the target injection start timing and the actual injection start timing to set the final target command pulse output timing. Based on the final target command pulse output timing, The electromagnetic valve is controlled so that the injection start timing of the first time coincides with the target injection start time. Further, the stop of the decrease in the common rail pressure indicates that the fuel injection is stopped. Therefore, the timing when the stop of the decrease in the common rail pressure is detected is the injection end timing. The time interval between the injection start timing and the fuel injection end timing is the injection period.
[0027]
In the fuel injection method of the engine, the injection characteristic is a total injection amount, and the basic target control amount is a basic target output to an electromagnetic valve provided in an injector for controlling opening and closing of the injection hole. This is the basic target total command pulse width calculated according to the target total injection amount in the command pulse, and the final target control amount is the basic target total command pulse width so that the total injection amount matches the target total injection amount. This is the corrected final target total command pulse width.
[0028]
In the fuel injection method of the engine, the injection characteristic is an initial injection amount, and the basic target control amount is a basic target output to an electromagnetic valve provided in an injector for controlling opening and closing of the injection hole. The basic target initial command pulse width calculated according to the target initial injection amount corresponding to the target total injection amount in the initial command pulse, and the final target control amount is set so that the initial injection amount becomes equal to the target initial injection amount. Is the final target initial command pulse width obtained by correcting the basic target initial command pulse width.
[0029]
The total injection amount and the initial injection amount can be opened and closed to release the pressure in the solenoid, armature, and balance chamber even when the supply start and stop points of the current (command pulse) that excites the solenoid of the solenoid valve of the injector are known. Response time delay and response speed, such as the behavior of valves and needle valves, differ from one injector to another. However, as described above, when the differential of the common rail pressure is integrated over the corresponding injection period as to the total injection amount and the initial injection amount, the integrated value corresponds to the injection amount. Further, since the initial injection period can be regarded as a fixed period predetermined for the engine, an amount corresponding to the initial injection amount is calculated by integrating the differential value of the common rail pressure over this period. Therefore, regardless of the presence or absence of variations in the injector characteristics, amounts corresponding to the actual total injection amount and the initial injection amount are always detected.
[0030]
A basic target command pulse is output to the solenoid valve provided in the injector for controlling the opening and closing of the nozzle hole. However, a map or the like is used based on the operating state of the engine detected by the sensor. The basic target total command pulse width is calculated in accordance with the determined target total injection amount. This basic target total command pulse width is sequentially corrected based on the comparison between the target total injection amount and the actual total injection amount calculated based on the differential of the common rail pressure, and the final target total command pulse width is set. The solenoid valve is controlled based on the final target total command pulse width so that the actual total injection amount matches the target total injection amount.
[0031]
A basic target initial command pulse is set for initial injection for the solenoid valve provided in the injector for controlling opening and closing of the nozzle hole, but a map or the like based on the operating state of the engine detected by the sensor The basic target initial command pulse width is calculated according to the target total injection amount obtained in step (1). This basic target initial command pulse width is sequentially corrected based on the comparison between the target initial injection amount and the actual initial injection amount calculated based on the differential of the common rail pressure, and the final target initial command pulse width is set. The solenoid valve is controlled based on the final target initial command pulse width so that the actual initial injection amount matches the target initial injection amount.
[0032]
Further, in the fuel injection method of the engine, the engine has a plurality of cylinders, and the correction of the basic target control amount for the injector provided in each cylinder is obtained at the time of the previous fuel injection for the injector. This is based on the injection characteristics.
[0033]
  In addition, this inventionEngine fuel injection device byA common rail that stores fuel delivered by a fuel pump, an injector that injects the fuel supplied from the common rail through a fuel flow path into an engine combustion chamber, a sensor that detects an operating state of the engine, and A controller that sets a target injection characteristic based on a detection signal from the sensor and sets a basic target control amount corresponding to the target injection characteristic in order to execute the fuel injection by the injector;In the fuel injection device for an engine, the fuel pump is connected to the common rail through a flow rate control valve that receives a control signal from the controller and controls a delivery amount of the fuel to the common rail.The controller obtains an injection characteristic of the injector based on a differential as a rate of change of the fuel pressure in the common rail with the passage of time with the fuel injection, and eliminates a variation in the injection characteristic of the injector. A final target control amount obtained by correcting the basic target control amount based on the target injection characteristic and the injection characteristic is set, and the injection characteristic by the injector is controlled based on the final target control amount.The injection characteristic is a maximum injection rate, the target injection characteristic is a target maximum injection rate, and the basic target control amount is a basic target command pulse output timing to a flow control valve, The final target control amount is a final target command pulse output timing to the flow control valve obtained by correcting the basic target command pulse output timing based on the maximum injection rate and the target maximum injection rate.
[0034]
  According to the engine fuel injection device, the target injection characteristic is set based on the detection signal from the sensor that represents the operating state of the engine, and the basic target corresponding to the target injection characteristic for executing the fuel injection by the injector. A controlled variable is set. On the other hand, the injection characteristic of the injector is obtained based on the differentiation as the rate of change with time of the fuel pressure in the common rail accompanying the fuel injection. Even if the target injection characteristic and the injection characteristic do not match due to variations in the fuel injection device including the injector, the basic target control amount in the fuel injection by the injector is based on the comparison between the target injection characteristic and the injection characteristic. Is corrected to set the final target control amount. Based on this final target control amount, the injection characteristic by the injector is controlled so that the target injection characteristic and the injection characteristic coincide.Further, the discharge period from the fuel pump is controlled based on a control signal from the controller to the flow control valve, and as a result, the common rail pressure is controlled. Furthermore, since the command pulse output timing to the flow control valve is corrected based on the maximum injection rate and the target maximum injection rate, the amount of fuel discharged from the fuel pump to the common rail is controlled, thereby the common rail pressure, That is, the fuel pressure injected from the injector is controlled, and finally the control is performed so that the variation of the maximum injection rate with respect to the target maximum injection rate is eliminated.
[0037]
  The engine fuel injection device according to the present invention includes a common rail for storing fuel delivered by a fuel pump, an injector for injecting the fuel supplied from the common rail through a fuel flow path into a combustion chamber of the engine, A sensor for detecting the operating state of the engine, a target injection characteristic is set based on a detection signal from the sensor, and a basic target control amount corresponding to the target injection characteristic is set in order to execute the fuel injection by the injector Equipped with a controller
In the fuel injection device for an engine, the injector includes an electromagnetic valve that opens and closes the nozzle hole in response to a control signal from the controller. The controller controls the fuel pressure in the common rail as the fuel is injected. Based on the derivative as a rate of change with time, the injection characteristic of the injector is obtained, and in order to eliminate variations in the injection characteristic of the injector, the basic target control amount is determined based on the target injection characteristic and the injection characteristic. A corrected final target control amount is set, and the injection characteristic of the injector is controlled based on the final target control amount. The injection characteristic is an injection start timing. The target injection characteristic is a target injection characteristic. The target control amount is a basic target command pulse output timing to the solenoid valve, and the final target control Amount, characterized in that it is a final target command pulse output timing of the solenoid valve is corrected based on the basic target command pulse output timing to the target injection start timing and the injection start timing.
[0038]
  According to the engine fuel injection device, the target injection characteristic is set based on the detection signal from the sensor that represents the operating state of the engine, and the basic target corresponding to the target injection characteristic for executing the fuel injection by the injector. A controlled variable is set. On the other hand, the injection characteristic of the injector is obtained based on the differentiation as the rate of change with time of the fuel pressure in the common rail accompanying the fuel injection. Even if the target injection characteristic and the injection characteristic do not match due to variations in the fuel injection device including the injector, the basic target control amount in the fuel injection by the injector is based on the comparison between the target injection characteristic and the injection characteristic. Is corrected to set the final target control amount. Based on this final target control amount, the injection characteristic by the injector is controlled so that the target injection characteristic and the injection characteristic coincide. Further, by controlling the opening / closing timing and opening / closing period of the solenoid valve, it is possible to control the timing and amount of fuel injection from the injection hole of the injector. Further, since the command pulse output timing to the solenoid valve is corrected based on the injection start timing and the target injection start timing, the valve opening timing of the solenoid valve is set so that the injection start timing matches the target injection start timing. As a result, variation of the injection start timing with respect to the target injection start timing is suppressed.
[0039]
In a fuel injection device for an engine in which an injector includes an electromagnetic valve, the injection characteristic is a total injection amount, the target injection characteristic is a target total injection amount, and the basic target control amount is a basic target total command pulse to the electromagnetic valve. The final target control amount is a final target total command pulse width to the solenoid valve obtained by correcting the basic target total command pulse width based on the total injection amount and the target total injection amount. Since the total command pulse width to the solenoid valve is corrected based on the total injection amount and the target total injection amount, the valve opening period of the solenoid valve is controlled so that the total injection amount matches the target total injection amount. As a result, the variation of the total injection amount with respect to the target total injection amount is suppressed.
[0040]
In an engine fuel injection device including an electromagnetic valve in an injector, the injection characteristic is an initial injection amount, the target injection characteristic is a target initial injection amount, and the basic target control amount is a basic target initial command pulse to the electromagnetic valve. The final target control amount is a final target initial command pulse width obtained by correcting the basic target initial command pulse width based on the initial injection amount and the target initial injection amount. Since the initial command pulse width to the solenoid valve is corrected based on the initial injection amount and the target initial injection amount, the initial valve opening period of the solenoid valve is controlled so that the initial injection amount matches the target initial injection amount. As a result, variation of the initial injection amount with respect to the target initial injection amount is suppressed.
[0041]
In the fuel injection device of the engine, the engine has a plurality of cylinders provided with injectors, and the correction of the basic target control amount is an injection obtained at the time of the previous fuel injection for each injector provided in the cylinder. This is done based on characteristics. The fuel injection characteristics are different for each injector due to variations caused by the dimensions and assembly accuracy of parts in the manufacturing process and assembly process. In the case of a multi-cylinder engine, the injection characteristics are different for each injector. It is necessary to obtain and correct the basic target control amount. In addition, by always executing this correction, it is possible to cope with the secular change of the injection characteristics for each injector.
[0042]
In the fuel injection device for the engine, the detection signal of the sensor, in particular, the common rail pressure that needs to be differentiated at high speed, is converted into a digital signal and then input to the controller via a high speed arithmetic element. . An example of a high-speed computing element is a DSP. By providing a high-speed calculation element on the sensor side, the calculation burden on the controller can be reduced.
[0043]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an engine fuel injection method and apparatus according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a view showing a main routine of engine control showing the control timing and order of cylinders by the engine fuel injection device according to the present invention, and FIG. 2 is a view showing a control routine of each cylinder of the flow in FIG. 3 is a diagram showing a target injection amount setting routine in the cylinder control in FIG. 2, FIG. 4 is a diagram showing a fuel pump control routine in the cylinder control in FIG. 2, and FIG. 5 is a diagram in FIG. FIG. 6 is a diagram showing an injector control routine in cylinder control, FIG. 6 is a diagram showing a final target command pulse output timing setting routine for the solenoid valve in the injector control routine shown in FIG. 5, and FIG. FIG. 8 is a diagram showing a final target total command pulse width setting routine for the solenoid valve in the injector control routine shown in FIG. FIG. 9 is a diagram showing a final target initial command pulse width setting routine for the solenoid valve in the control routine of the actuator, FIG. 9 is a diagram showing an injection rate measurement routine in the cylinder control in FIG. 2, and FIG. FIG. 9 is a diagram showing a calculation routine of each feedback correction amount read in FIG. 6, FIG. 7 and FIG. The common rail fuel injection system to which the fuel injection device for an engine according to the present invention is applied and the injector used in the system may be the same as the conventional one already described with reference to FIGS.
[0044]
Hereinafter, the case where the procedure of the fuel injection control according to the present invention performed by the controller 12 is applied to a four-cycle, four-cylinder diesel engine will be described. The engines are sequentially arranged in a line from the first cylinder to the fourth cylinder with respect to the crankshaft, and the ignition order is the order of the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder.
[0045]
As shown in FIGS. 12 and 13, this system mainly includes a fuel pump 8 that is a variable capacity high-pressure pump that rotates in synchronization with the crankshaft of the engine, and a common rail that stores fuel pressurized by the fuel pump 8. 2. Injector 1 for injecting high-pressure fuel in common rail 30 into each cylinder, various sensors 40 to 47 for detecting the operating state of the engine, and sending a control signal to fuel pump 8 and injector 1 according to the operating state of the engine Thus, the controller 12 is configured to control fuel injection. The fuel in the fuel tank 4 is pressurized by the fuel pump 8 and supplied to the common rail 2.
[0046]
The fuel pump 8 has a fuel pressurizing chamber (not shown) in which one or more plungers (not shown) that are stroked by a cam are incorporated. It is selectively connected to the return pipe 10. The fuel pipe 9 is connected to the common rail 2, and the return pipe 10 is connected to the fuel tank 4. The flow control valve 15 normally has a fuel pressurizing chamber connected to the return pipe 10, but receives a command pulse from the controller 12 at an arbitrary time during the fuel pressure feeding stroke by the plunger, and thereafter the plunger A system in which the fuel pressurizing chamber is connected to the fuel pipe 9 is used until the end of the pumping stroke.
[0047]
The end of the pressure-feed stroke of the plunger is uniquely determined by a cam that is rotated by the output of the engine. By controlling the command pulse supply start timing, that is, the fuel pump start timing by the plunger, the fuel pumping amount per stroke of the plunger, that is, the fuel filling amount to the common rail 2 can be controlled. Therefore, it is possible to control the fuel pressure in the common rail (hereinafter referred to as the common rail pressure) by setting a period for connection to the common rail 2 during the discharge period of the fuel pump 8. As the flow control valve, a general duty solenoid valve or the like may be used in addition to the above-mentioned type.
[0048]
The common rail pressure is supplied to the injector 1 of each cylinder through the branch pipe 3. The injector 1 includes a balance chamber 30 and an electromagnetic valve 26 for controlling the opening and closing of the needle valve, in addition to the nozzle hole and the needle valve that opens and closes the nozzle hole. Most of the high-pressure fuel supplied to the injector 1 is led to the vicinity of the injection hole to give a valve opening force to the needle valve, and a part is introduced into the balance chamber 30 to give a valve closing force to the needle valve. .
[0049]
When a command pulse is supplied to the electromagnetic valve 26, the balance chamber 30 is connected to the return pipe 10, the pressure in the balance chamber 30 drops, the needle valve lifts and opens, and fuel injection is executed. Therefore, the fuel injection timing and the fuel injection period of the injector 1 are controlled by controlling the supply timing and supply period (command pulse width) of the command pulse to the electromagnetic valve 26. Here, since the fuel in the common rail 2 is controlled to a predetermined pressure, the injection amount can be substantially controlled by controlling the injection period. The injector 1 may be of the type in which the balance chamber 30 is omitted and the needle valve is directly driven by an electromagnetic solenoid or a piezoelectric element.
[0050]
As a sensor for detecting the operating state of the engine, for example, the following may be mentioned as a minimum.
(1) Engine speed sensor 40
The engine speed sensor 40 includes a gear plate having a predetermined number of teeth (for example, 36 teeth) attached to the crankshaft and a pickup sensor, and the time required for pulse input for a certain number of teeth (for example, 18 teeth) is determined from that time. The rotation speed Ne is calculated.
(2) Cylinder discrimination sensor 41
The cylinder discrimination sensor 41 detects a reference signal for the controller to discriminate the control cylinder. A gear plate having teeth (one tooth) corresponding to a specific crank angle (for example, TDC) of a specific cylinder (for example, the first cylinder) attached to the camshaft of the high pressure fuel pump or the camshaft for driving the intake / exhaust valve And a pickup sensor.
(3) Top dead center (TDC) sensor 42
The top dead center sensor 42 detects the top dead center (TDC) top dead center of each cylinder. A gear plate having teeth (for example, 4 teeth) corresponding to the TDC of each cylinder, which is attached to the camshaft of the fuel pump 8 or the camshaft for driving the intake / exhaust valve, includes a pickup sensor.
(4) Accelerator pedal depression amount sensor 43
The accelerator pedal depression amount sensor 43 detects the depression amount Acc of the accelerator pedal.
(5) Common rail pressure sensor 13
The fuel pressure in the common rail is detected.
[0051]
In the above system, the controller 12 executes routines shown in the following flowcharts. As shown in FIG. 1, the “main routine” controls the fuel injection for each cylinder. That is, when the pulse generation timing of the cylinder discrimination sensor 41 is set to the top dead center of the first cylinder, the control of each cylinder is executed as follows. FIG. 11 shows the common rail pressure, its derivative, and how each signal changes over time.
[0052]
(1) When the first cylinder reaches top dead center, the cylinder discrimination sensor 41 generates a pulse signal as a cylinder discrimination signal, and the generated cylinder discrimination signal is input to the controller 12 (abbreviated as step 1 and S1). same as below).
(2) The first cylinder top dead center sensor 42 detects that the first cylinder is at top dead center, and a pulse signal as a top dead center signal is input to the controller 12 (S2).
(3) When the first cylinder reaches the top dead center, the cylinder in which combustion is performed next is the third cylinder that has already finished the intake stroke and shifts to the compression stroke, so the third cylinder control is performed ( S3). That is, fuel injection control is executed for the third cylinder.
(4) When the third cylinder reaches the top dead center, a pulse signal as a top dead center signal from the top dead center sensor 42 of the third cylinder is input to the controller 12 (S4).
In the same manner,
(5) Control of the fourth cylinder (S5),
(6) Input to the controller 12 of a pulse signal from the top dead center sensor 42 of the fourth cylinder that has detected that the fourth cylinder has reached top dead center (S6),
(7) Control of second cylinder (S7),
(8) Input to the controller 12 of a pulse signal from the TDC sensor 43 of the second cylinder that has detected that the second cylinder has reached top dead center (S8),
(9) Further, control of the first cylinder (S9) is executed.
The crankshaft rotates twice during the main routine. During this time, the camshaft may be rotated once for intake and exhaust. And the above-mentioned main routine is repeated during engine operation.
[0053]
The fuel injection control for the first to fourth cylinders in S3, S5, S7 and S9 is executed according to the “cylinder control routine” shown in FIG. As the execution of the cylinder control routine starts, the clock in the controller 12 counts time (T_n). In the cylinder control routine, each control is executed as follows.
(1) In the “target injection amount setting” step, a target total injection amount to be injected by one fuel injection from the injector 1 is set for each cylinder (S11). The target total injection amount is set according to a preset map or the like based on the operating state of the engine detected by each sensor.
(2) In the step of “control of the fuel pump”, the fuel pump is controlled in order to control the pressure of the common rail giving the fuel injection pressure so that the set target total injection amount can be obtained (S12). .
(3) In the “injector control” step, the injection control of the injector 1 is performed under the common rail pressure controlled in S12 (S13). When the cylinder control routine is repeated, the basic target control amount is set and set corresponding to the target injection characteristic determined from the target total injection amount obtained in S11 and the common rail pressure controlled in S12. The basic target control amount is corrected by the feedback correction amount (described later in (5)) obtained in the previous cylinder control routine, and the fuel injection of the injector 1 is controlled according to the final target control amount obtained as a result of the correction. Is done.
(4) In the “measurement of injection rate” step, the injection rate of the fuel injected by each injector is measured (S14).
(5) In the step of “calculation of feedback correction amount”, feedback correction for correcting the basic target control amount so as to eliminate variations in the injection characteristics of the injectors, that is, so that the actual injection characteristics coincide with the target injection characteristics. An amount is determined (S15). The obtained feedback correction amount is used for correcting the basic target control amount in S13 for the same injector in the next cylinder control routine.
Thus, although each said step S11-S15 is performed in this order about each injector, the detail is demonstrated for every said step below.
[0054]
The setting of the target injection amount of fuel from the injector in S11 is executed in accordance with the “target injection amount Qtf setting routine” shown in the flowchart of FIG.
(1) After the start, the engine speed Ne detected by the engine speed sensor 40 and the accelerator depression amount sensor 43 and the accelerator depression amount Acc are input to the controller 12 as parameters representing the basic engine operating state. The In addition, as a parameter representing an additional engine operating state, the coolant temperature (Tw), the intake pipe pressure (Pb), and the like are detected by each sensor and input to the controller 12 (S101).
(2) Based on the engine speed Ne and the accelerator depression amount Acc, the basic target total injection amount Qtb obtained from the basic injection amount characteristic shown in FIG. It is read (S102).
(3) A difference ΔQ with respect to the previous execution total injection amount Qtp in the cylinder, that is, an increase / decrease amount of the injected fuel in the same cylinder is obtained (S103).
(4) These parameters are determined in advance corresponding to each parameter (engine speed Ne, ΔQ itself, cooling water temperature Tw, intake pipe pressure Pb, etc.) representing the operating state of the engine detected in S101. A correction coefficient K for correcting ΔQ is obtained by the function G (S104). That is, K = G (Ne, ΔQ, Tw, Pb, etc)
(5) The current final target total injection amount Qtf corresponding to the operating state of the engine is calculated by the following equation using ΔQ obtained in S103 and the correction coefficient K obtained in S104 with respect to the previous execution total injection amount Qtp. Obtain and set (S105).
Qtf = Qtp + K · ΔQ
Note that the method of correcting ΔQ is adopted to obtain the final target total injection amount Qtf this time. However, the present invention is not limited to this, and when the basic injection amount characteristic is obtained from the two-dimensional map basic injection amount data, the accelerator depression amount The current final target total injection amount Qtf may be directly obtained by correcting Acc in advance based on the operating state of the engine.
[0055]
The control of the fuel pump is executed according to the “fuel pump control routine” shown in the flowchart of FIG.
(1) The current final target total injection amount Qtf set in S105 and the engine speed Ne are read (S201).
(2) The target maximum injection rate Rmaxb is obtained and set based on a map prepared in advance corresponding to the current final target total injection amount Qtf and the engine speed Ne read in S201 (S202). . The target maximum injection rate Rmaxb is one of target injection characteristics in the fuel injection control of the engine according to the present invention.
(3) Corresponding to the target maximum injection rate Rmaxb set in S202, the target common rail pressure Pcf is obtained and set by a predetermined function (S203).
(4) Next, the current measured value of the actual common rail pressure Pc is input (S204).
(5) Basic target command pulse output timing to the flow control valve 15 of the fuel pump 8 by the function H regarding the deviation between the target common rail pressure Pcf set in S203 and the current actual common rail pressure Pc measured in S204 PTpb is obtained by calculation (S205). The basic target command pulse output timing PTpb to the flow control valve 15 is one of basic target control amounts in the fuel injection control of the engine according to the present invention.
(6) A feedback correction amount PTpc (which will be described later) for correcting the command pulse output timing to the flow control valve 15 is obtained (S206).
(7) The basic target command pulse output timing PTpb is corrected by adding the feedback correction amount PTpc determined in S206 to the basic target command pulse output timing PTpb determined in S205 as follows. By this correction, the final target command pulse output timing PTpf to the flow control valve 15 is obtained and set. The final target command pulse output timing PTpf to the flow control valve 15 is one of the final target control amounts in the fuel injection control of the engine according to the present invention.
PTpf = PTpb + PTpc
(8) Thereafter, the final target command pulse output timing PTpf to the flow rate control valve 15 has arrived by the clock being timed, that is, T_nIt is determined whether or not = PTpf (S208). If the final target command pulse output time PTpf has not arrived, S208 is repeated until it arrives.
(9) When it is determined in S208 that the final target command pulse output timing PTpf has arrived, a command pulse PWp (a constant value) is output to the flow control valve 21, and fuel is supplied from the fuel pump 8 to the common rail 2. Thus, the fuel pressure in the common rail 2 is controlled so that the fuel pressure is such that the target maximum injection rate Rmaxb is obtained (S209).
[0056]
Next, the control of the injector is executed according to the “injector control routine” shown in the flowchart of FIG.
(1) The current final target total injection amount Qtf set in S105 and the engine speed Ne are read (S301).
(2) The actual measured value of the common rail pressure Pc when the control of the fuel pump by S2 is completed is input (S302).
(3) The final target command pulse output timing PTif, final target total command pulse width PWitf, and final target initial command pulse width PWief to the solenoid valve 26 of the injector 1 are obtained and set by respective routines to be described later ( S303). These output timing PTif, total command pulse width PWitf, and initial command pulse width PWief for the final target command pulse to the solenoid valve 26 of the injector 1 constitute the final target control amount in the fuel injection control of the engine according to the present invention. Yes.
(4) Thereafter, the final target command pulse output timing PTif to the solenoid valve 26 of the injector 1 has arrived by the clock being timed, that is, T_nIt is determined whether or not = PTif (S304). If the final target command pulse output timing PTif has not arrived, S304 is repeated until it arrives.
(5) When it is determined that the final target command pulse output timing PTif has arrived, the command pulse to the solenoid valve 26, that is, the final target total command pulse width PWitf and the final target initial command pulse width PWief are output. (S305).
[0057]
Here, the setting of the final target command pulse output timing PTif, the final target total command pulse width PWitf, and the final target initial command pulse width PWief will be described in more detail with reference to the setting routines shown in FIGS. .
[0058]
The final target command pulse output timing PTif for the electromagnetic valve 26 of the injector 1 will be described based on the “setting routine for the final target command pulse output timing PTif for the electromagnetic valve” shown in FIG.
(1) The current final target total injection amount Qtf set in S105 and the engine rotational speed Ne are read, and corresponding to the input values based on the two-dimensional map target injection timing data prepared in advance. The target injection timing Tif is obtained and read by the controller 12 (S311). The target injection timing Tif is one of target injection characteristics.
(2) The basic target command pulse output timing PTib as the basic target control amount is taken into consideration with respect to the target injection timing Tif read in S311 in consideration of electromagnetic and mechanical response delays from the solenoid valve 26 to the needle valve 24. It is set (S312).
(3) Next, for the command pulse output timing to the solenoid valve 26, the feedback correction amount PTic (which will be described later in the detailed description of S5) already read in the previously executed cylinder control routine is read. S313).
(4) The basic target command pulse output timing PTib is corrected by adding the feedback correction amount PTic read in S313 to the basic target command pulse output timing PTib set in S312 and the final target as the final target control amount is corrected. The command pulse output timing PTif is obtained and set (S314).
[0059]
The final target total command pulse width PWitf for the electromagnetic valve 26 of the injector 1 will be described based on the “setting routine for the final target total command pulse width PWitf for the electromagnetic valve” shown in FIG.
(1) The two-dimensional map basic target total corresponding to the current final target total injection amount Qtf set in S105 and the actual common rail pressure Pc obtained when the control of the fuel pump in S2 determined in S302 is completed. Based on the command pulse width data, the basic target total command pulse width PWitb is obtained and read (S321). In setting the final target total command pulse width PWitf for the solenoid valve, the current final target total injection amount Qtf is the target injection characteristic.
(2) Next, for the command pulse to the solenoid valve 26, the feedback correction amount PWitc of the total command pulse width already obtained in the previously executed cylinder control routine (described later in the detailed description of S5) is It is read (S322).
(3) The basic target total command pulse width PWitb is corrected by adding the feedback correction amount PWitc of the total command pulse width read in S322 to the basic target total command pulse width PWitb set in S321, and the final target control The final target total command pulse width PWitf as a quantity is obtained and set (S323).
[0060]
The final target initial command pulse width PWief for the electromagnetic valve 26 of the injector 1 will be described based on the “setting routine for the final target initial command pulse width PWief for the electromagnetic valve” shown in FIG.
(1) Corresponding target based on two-dimensional map target initial injection amount data prepared in advance corresponding to the current final target total injection amount Qtf set in S105 and the read engine speed Ne. The initial injection amount Qef, that is, the target injection amount during the ignition delay period te (a constant value) is obtained and read into the controller 12 (S331). In setting the final target initial command pulse width PWief for the solenoid valve, the target initial injection amount Qef is the target injection characteristic.
(2) The basic target initial command pulse width PWieb is determined based on the two-dimensional map basic target initial command pulse width data prepared in advance corresponding to the target initial injection amount Qef read in S331 and the common rail pressure Pc. It is obtained and read (S332).
(3) Next, regarding the command pulse to the solenoid valve 26, the feedback correction amount PWiec of the initial command pulse width already obtained in the cylinder control routine executed last time (described later in the detailed description of S5) is It is read (S333).
(4) The basic target initial command pulse width PWieb is corrected by adding the feedback correction amount PWiec of the initial command pulse width read in S333 to the basic target initial command pulse width PWieb set in S332, thereby correcting the final target initial command pulse width PWieb. The command pulse width PWief is obtained and set (S334).
[0061]
Next, the injection rate measurement will be described in more detail based on the “injection rate measurement routine” shown in FIG. The injection rate measurement routine is executed by the following steps simultaneously with the output of the command pulse in the injector control routine.
(1) Following the start, the time (T_n) Common rail pressure Pc (T_n) Is detected and stored in the memory of the controller 12 (S401).
(2) The common rail pressure Pc (T_n) And common rail pressure Pc (T_n-1) From the differential value R (T of the common rail pressure Pc_n) Is obtained by the calculation of the following equation (S402). Note that ΔPc / ΔT to R (T_nThe conversion factor to) is obtained by testing or the like.

(3) Next, it is determined whether an injection execution flag (details will be described later) is ON / OFF. If the injection execution flag is OFF, the routine proceeds to routine 410. If the injection execution flag is ON, Then, the routine proceeds to routine 420 (S403). However, the first time shifts to the routine 410.
(4) In the routine 410, the differential value R of the common rail pressure Pc is compared with a predetermined slice level (injection execution determination value) Rl (S411). When R is equal to or less than Rl, that is, when the injection is not performed and the change rate of the common rail pressure Pc is small, it is determined that the injection is not started, the process returns to the start, and the common rail pressure Pc ( T_n) Detection continues.
(5) While repeating the above, actual injection is started, and when the differential value R of the common rail pressure Pc exceeds the injection execution determination value Rl, the injection flag is turned on (S412), and the time Tis at that time is The injection start time is stored in the memory (S413).
(6) Returning to the start again and executing S401 and S402, the injection flag is ON, so the routine proceeds to routine 420 in S403.
(7) In the routine 420, the differential value R of the common rail pressure Pc is again compared with the injection execution determination value Rl (S421), and while the injection execution determination value Rl is exceeded, the routine returns to the start and the common rail pressure Pc (T_n) Detection continues.
(8) Eventually, when the actual injection is finished and the differential value R of the common rail pressure Pc becomes equal to or less than the injection execution determination value R1, there is almost no change in the common rail pressure Pc, that is, the fuel injection is finished. Therefore, through the determination in S421, the injection flag is turned off (S422), and the time Tie at that time is stored in the memory as the injection end time (S423).
(9) For the time from the injection start time Tis to the injection end time Tie, the total injection amount Qt executed by integrating the differential value R of the common rail pressure Pc is obtained and stored in the memory (S424).
(10) The initial injection amount Qe executed by integrating the differential value R of the common rail pressure Pc over the initial injection period te (that is, the ignition delay period) starting from the injection start time Tis is obtained and stored in the memory ( S425).
(11) The maximum value of the differential value R of the common rail pressure Pc (for example, the average value of the differential values R at a plurality of points in the vicinity of the maximum value) is stored in the memory as the maximum injection rate Rmax (S426).
[0062]
Finally, feedback correction amount calculation will be described based on the “feedback correction amount calculation routine” shown in FIG. A correction amount for each basic target control amount is obtained from each target injection characteristic obtained in the execution of the fuel pump control routine and the injector control routine and each executed injection characteristic measured in the injection rate measurement routine. . Each correction amount is calculated as a predetermined function corresponding to the deviation between the target injection characteristic and the previously executed injection characteristic.
[0063]
First, in the feedback correction amount PTic routine 510, the feedback correction amount of the command pulse output timing to the solenoid valve 26 of the injector 1 is actually measured as the target injection timing Tif as the target injection characteristic in the control of the command pulse output timing. It is calculated | required from the injection start time Tis as an injection characteristic. That is, since the actual injection start time is Tis, the target injection timing Tif and the injection start time Tis for the injector are read (S511), and feedback correction is performed by the function U with respect to the deviation (Tif−Tis) between the two. The amount PTic is determined (S512). The obtained feedback correction amount PTic is read in the final target command pulse output timing setting routine for the solenoid valve shown in FIG. 6 (S313), and is added to the basic target command pulse output timing PTib set in S312. The final target command pulse output timing PTif to the first solenoid valve 26 is set as the final target control amount (S314).
[0064]
Next, in the feedback correction amount PWitc routine 520, the feedback correction amount of the total command pulse width to the solenoid valve 26 of the injector 1 is measured with the final target total injection amount Qtf as the target injection characteristic for the control of the total command pulse width. It is obtained from the total injection amount Qt as the actual injection characteristic. That is, since the actual total injection amount is Qt, the final target total injection amount Qtf and the total injection amount Qt for the injector are read (S521), and the function V for the deviation (Qtf−Qt) of both is read. A feedback correction amount PWitc is obtained (S522). The obtained feedback correction amount PWitc is read in the final target total command pulse width setting routine for the solenoid valve shown in FIG. 7 (S322), and is added to the basic target total command pulse width PWitb set in S321. The final target total command pulse width PWitf to the first solenoid valve 26 is set as the final target control amount (S323).
[0065]
Next, in the feedback correction amount PWiec 530, the feedback correction amount of the initial command pulse width to the solenoid valve 26 of the injector 1 is actually measured as the target initial injection amount Qef as the target injection characteristic for the control of the initial command pulse width. Is obtained from the initial injection amount Qe as the injection characteristic. That is, since the actual initial injection amount is Qe, the target initial injection amount Qef and the initial injection amount Qe for the injector are read (S531), and feedback is performed by the function Y for the deviation (Qef−Qe) between them. A correction amount PWiec is obtained (S532). The obtained feedback correction amount PWiec is read in a final target initial command pulse width setting routine for the solenoid valve shown in FIG. 8 (S333), and is added to the basic target initial command pulse width PWieb set in S332, and the injector The final target initial command pulse width PWief to the first solenoid valve 26 is set as the final target control amount (S334).
[0066]
Finally, in the feedback correction amount PTpf routine 540, the feedback correction amount of the command pulse output timing to the flow rate control valve 15 of the fuel pump 8 is set to the target maximum injection rate Rmaxb as the target injection characteristic for the control of the command pulse output timing. It is obtained from the measured maximum injection rate Rmax as actual injection characteristics. That is, since the actual maximum injection rate is Rmax as determined in S426 shown in FIG. 9, the target maximum injection rate Rmaxb and the maximum injection rate Rmax for the injector are read (S541), and the deviation between them (Rmaxb The feedback correction amount PTpc of the command pulse output timing to the fuel pump is obtained as the feedback correction amount by the function Z for (−Rmax) (S542). The obtained feedback correction amount PTpc is read in the control routine of the fuel pump shown in FIG. 4 (S206) and added to the basic target initial command pulse output timing PTpb for the fuel pump set in S205. The final target command pulse output timing PTpf to the flow control valve 15 is set as the final target control amount (S207).
[0067]
Next, the time course of the control by the fuel injection device of the engine according to the present invention will be described along the time course based on FIG. It is assumed that the previous fuel injection control for the third cylinder has already been performed before two rotations of the crankshaft.
(1) When an output pulse of a cylinder discrimination signal CYL provided for the first cylinder is detected, a top dead center signal TDC indicating that the first cylinder has reached top dead center in accordance with the fall. Is output. In response to the fall of the top dead center signal TDC, the rise of the pulse signal from the engine speed sensor 40 comprising a gear plate having a predetermined number of teeth (for example, 36 teeth) attached to the crankshaft and a pickup sensor. In response to the fall, the clock T in the controller 12_nStarts timing (T_n= 0). The pulse signal from the engine speed sensor 40 is always input to the controller 12 together with the accelerator pedal depression amount Acc. Furthermore, the common rail pressure Pc is also the clock T._nIs detected to be a digital value in the end, and the adjacent clock T_nThe fuel injection rate is calculated as a value proportional to the change rate at. Based on the top dead center signal TDC indicating that the first cylinder has reached the top dead center, the fuel injection of the third cylinder that next arrives at the top dead center is controlled.
[0068]
(2) The current basic target total injection amount Qtb is obtained from the two-dimensional map target injection amount data based on the engine speed Ne and the accelerator depression amount Acc, and is corrected based on a deviation from the previous basic target total injection amount Qptb. This final target total injection amount Qtf is set. A target maximum injection rate Rmaxb is set from the two-dimensional map target maximum injection rate data based on the set final target total injection amount Qtf and the engine speed Ne. In order to obtain the target maximum injection rate Rmaxb, the target common rail pressure Pcf is set, and the basic target command pulse output timing PTpb to the flow control valve 15 provided on the discharge side of the fuel pump 8 according to the deviation from the current common rail pressure Pc. Is determined. That is, since the fuel is sent from the fuel pump 8 to the common rail 2 through the flow rate control valve 15 between the basic target command pulse output timing PTpb and the end point of the plunger stroke, the magnitude of the common rail pressure Pc is set according to the feeding period. Can be controlled. The earlier the basic target command pulse output timing PTpb, the greater the common rail pressure Pc when fuel injection should be performed.
[0069]
However, the target maximum injection rate Rmaxb cannot be obtained correctly only by the above-described method due to variations in individual parts of the fuel supply system and aging. Accordingly, the discrete injection rate R (T) based on the differential (change rate) of the common rail pressure Pc at the time of the previous fuel injection._n) Is averaged to obtain a feedback correction amount PTpc corresponding to the deviation between the target maximum injection rate Rmaxb and the previous maximum value of the injection rate R by the same cylinder, and the current basic target command pulse output A final target command pulse output timing PTpaf obtained by correcting the timing PTpb with the feedback correction amount PTpc is set, and a command pulse to the flow control valve is output at the final target command pulse output timing PTpaf.
[0070]
(3) As defined in (2) above, a fuel injection command is sent from the controller 12 to the solenoid valve 26 of the injector 1 when the common rail pressure is maximized. When the engine speed Ne and the set final target total injection amount Qtf are read and the common rail pressure Pc is input, a map or the like is based on the final target total injection amount Qtf and the engine speed Ne or the common rail pressure Pc. Thus, three injection conditions for the solenoid valve 26 of the injector 1, that is, the basic target command pulse output timing PTib, the basic target total command pulse width PWitf, and the basic target initial command pulse width PWief are obtained from a map or the like. If the common rail pressure Pc has already been determined, the control of the fuel injection amount and the fuel injection rate can be determined almost uniquely by these three conditions of fuel injection by the injector 1.
[0071]
However, the above three quantities cannot be determined correctly only by the above-described method due to variations in individual parts of the fuel supply system and aging. Therefore, the common rail pressure Pc at the time of the previous injection is sequentially differentiated, and the above three amounts are corrected in the current fuel injection in the cylinder based on this differential value. That is, based on this differential value, the time Tis at which the common rail pressure Pc at the previous injection starts to change is actually obtained, and the command is calculated based on the deviation between Tis and the target injection timing Tif at the previous injection. The feedback correction amount PTic of the pulse output timing is obtained, and the basic target command pulse output timing PTib of the current injection is corrected by the feedback correction amount PTic at the time of the current injection in the cylinder.
[0072]
Further, since the basic target total command pulse width PWitf is an amount greatly related to the fuel injection amount, the total value obtained by integrating the differential value of the common rail pressure Pc during the previous injection over the injection period (Tie-Tis). Based on the deviation between the injection amount Qt and the target total injection amount Qtf, a feedback correction amount PWitc of the total command pulse width is obtained, and the basic target total command pulse width at the time of the current injection is calculated with the feedback correction amount PWitc. Correct PWitf.
[0073]
Further, with respect to the basic target initial command pulse width PWief, the deviation between the initial injection amount Qe obtained by integrating the differential value of the common rail pressure Pc at the previous injection over the initial injection period tf and the target initial injection amount Qef Based on this, a feedback correction amount PWiec of the initial command pulse width is obtained, and the basic target initial command pulse width PWief at the time of the current injection is corrected by the feedback correction amount PWiec.
[0074]
A signal from the pressure sensor 13 that detects the common rail pressure Pc is input to the CPU of the controller 12 via the A / D converter 16 and a DSP (Digital Signal Processor) 17 that is a high-speed calculation element. The calculation burden is reduced.
[0075]
【The invention's effect】
As described above, the fuel injection device for an engine according to the present invention uses the same injector to connect the fuel pump and the common rail based on various data obtained from the differential value of the common rail pressure at the time of the previous fuel injection. In the manufacture of each component that injects fuel, such as injectors, by correcting the amount of fuel injection this time for the command pulses to the flow rate control valves provided on the road and solenoid valves provided on the injectors In addition, fuel injection can be executed in the best condition by correcting variations in assembly and aging, suppressing the occurrence of HC (hydrocarbon) and soot in the exhaust gas due to combustion variations, and Engine noise and vibration can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing an engine control main routine showing the control timing and order of cylinders by an engine fuel injection device according to the present invention;
FIG. 2 is a diagram showing a control routine for each cylinder in the flow in FIG. 1;
FIG. 3 is a diagram showing a target injection amount setting routine in the cylinder control in FIG. 2;
4 is a diagram showing a control routine for a fuel pump in the cylinder control in FIG. 2. FIG.
FIG. 5 is a diagram showing an injector control routine in the cylinder control in FIG. 2;
6 is a diagram showing a final target command pulse output timing setting routine for the solenoid valve in the injector control routine shown in FIG. 5; FIG.
7 is a diagram showing a final target total command pulse width setting routine for the solenoid valve in the injector control routine shown in FIG. 5; FIG.
FIG. 8 is a diagram showing a final target initial command pulse width setting routine for the solenoid valve in the injector control routine shown in FIG. 5;
FIG. 9 is a diagram showing an injection rate measurement routine in the cylinder control in FIG. 2;
10 is a diagram showing a calculation routine of each feedback correction amount read in FIG. 4, FIG. 6, FIG. 7 and FIG.
FIG. 11 is a graph showing changes over time in each command, common rail pressure and injection rate by the engine fuel injection device according to the present invention;
FIG. 12 is a schematic view of a conventional common rail fuel injection system.
FIG. 13 is a cross-sectional view showing an example of an injector used in a conventional common rail fuel injection system.
FIG. 14 is a characteristic diagram showing the relationship between the fuel injection amount of the injector using the common rail pressure as a parameter and the command pulse width to the solenoid valve in the common rail fuel injection system.
FIG. 15 is a basic injection amount characteristic diagram showing a relationship between an engine speed and a basic injection amount with an accelerator pedal depression amount as a parameter in a common rail fuel injection system.
FIG. 16 is a graph showing a time course of a fuel injection rate of an injector by a conventional common rail fuel injection device.
[Explanation of symbols]
1 Injector
2 Common rail
3 branch pipe
7 Fuel pipe
8 Fuel pump
9 Fuel pipe
12 Controller
13 Pressure sensor
15 Flow control valve
17 DSP
25 injection hole
26 Solenoid valve
40 Engine speed sensor
41 cylinder sensor
42 Top dead center sensor
43 Accelerator pedal depression sensor
44 Cooling water temperature sensor
45 Air temperature sensor
46 Atmospheric pressure sensor
47 Intake pipe pressure sensor
Pc Common rail pressure
Qt Total injection amount
Qe Initial injection amount
Qtf Final target total injection amount
Qte Target initial injection amount
Rnaxb target maximum injection rate
Rmax Maximum injection rate
Tif target injection timing
Tis injection start time
PTpb Basic target command pulse output timing to flow control valve
PTpc PTpb feedback correction amount
PTpf Final target command pulse output timing to flow control valve
PTib Basic target command pulse output timing to solenoid valve
PTic PTib feedback correction amount
PTif The final target command pulse output timing to the solenoid valve
PWitb Basic target total command pulse width to solenoid valve
PWitc PWitb feedback correction amount
PWitf Final target total command pulse width to solenoid valve
PWieb Basic target initial command pulse width to solenoid valve
PWiec PWieb feedback correction amount
PWief Final target initial command pulse width to solenoid valve

Claims (13)

Fuel sent out by a fuel pump is stored in a common rail, the fuel supplied from the common rail through a fuel flow path is injected into an engine combustion chamber from an injection hole formed in an injector, and the operating state of the engine is detected by a sensor. And a controller sets a target injection characteristic based on a detection signal from the sensor and sets a basic target control amount corresponding to the target injection characteristic in order to execute the fuel injection by the injector and the basic In a fuel injection method for an engine that controls injection characteristics of the injector based on a target control amount,
In order to obtain the injection characteristics based on the differential as the rate of change of the fuel pressure in the common rail with the passage of time with the fuel injection, and to eliminate variations in the injection characteristics of the injector, the basic target control amount is set to A final target control amount corrected based on the target injection characteristic and the injection characteristic is set, and the injection characteristic by the injector is controlled based on the final target control amount. The injection characteristic includes at least the fuel A maximum injection rate calculated corresponding to the maximum value of the differential of the pressure, an injection start timing determined when the differential of the fuel pressure exceeds a predetermined value, and the differential of the fuel pressure over the fuel injection period The total injection amount obtained corresponding to the integrated value obtained by integration, or the integrated value obtained by integrating the derivative of the fuel pressure over the initial injection period. Contains an initial injection amount required, the and the target injection characteristic, engine, wherein at least the target maximum injection rate of the fuel, the target injection start timing, the target total injection quantity, or to include the target initial injection amount Fuel injection method. The engine fuel injection method according to claim 1, wherein the injection characteristic is obtained based on a smoothed characteristic curve of the differential . The injection characteristic is the maximum injection rate, and the basic target control amount is a basic target command pulse output to a flow control valve provided in the fuel flow path connecting the fuel pump and the common rail. Is a basic target command pulse output timing calculated according to the target maximum injection rate, and the final target control amount is the basic target command pulse output timing so that the maximum injection rate becomes equal to the target maximum injection rate. The fuel injection method for an engine according to claim 1 or 2 , wherein the final target command pulse output timing is corrected . The injection characteristic is the injection start timing, and the basic target control amount is a basic target command output to an electromagnetic valve provided in the injector for controlling opening and closing of the injection hole formed in the injector. A basic target command pulse output timing that is calculated according to the target injection start timing of the injector in a pulse, and the final target control amount is the basic target so that the injection start timing matches the target injection start timing. engine fuel injection method according to claim 1 or 2, characterized in that the command pulse output which time a final target command pulse output timing with the corrected. The injection characteristic is the total injection amount, and the basic target control amount is a basic target command that is output to an electromagnetic valve provided in the injector for controlling opening and closing of a control injection hole formed in the injector. A basic target total command pulse width calculated according to the target total injection amount in a pulse, and the final target control amount is calculated so that the total injection amount matches the target total injection amount. engine fuel injection method according to claim 1 or 2, characterized in Toko is corrected final target gross command pulse width width. The injection characteristic is the initial injection amount, and the basic target control amount is a basic target initial output that is output to an electromagnetic valve provided in the injector to control opening and closing of the injection hole formed in the injector. A basic target initial command pulse width calculated according to a target initial injection amount corresponding to the target total injection amount in a command pulse, and the final target control amount is equal to the initial initial injection amount. the basic target initial command engine fuel injection method according to claim 1 or 2, characterized in that the pulse width is corrected final target initial command pulse width so. The engine has a plurality of cylinders, and the correction of the basic target control amount for the injector provided in each cylinder is based on the injection characteristic obtained at the time of the previous fuel injection for the injector. The engine fuel injection method according to claim 1, wherein the fuel injection method is performed. A common rail for storing fuel delivered by a fuel pump, an injector for injecting the fuel supplied from the common rail through a fuel flow path into an engine combustion chamber, a sensor for detecting an operating state of the engine, and the sensor A controller for setting a target injection characteristic based on a detection signal from the engine and setting a basic target control amount corresponding to the target injection characteristic for executing injection of the fuel by the injector, wherein the fuel pump includes the controller In a fuel injection device for an engine connected to the common rail through a flow rate control valve that receives a control signal from the fuel and controls a delivery amount of the fuel to the common rail,
The controller obtains an injection characteristic of the injector based on a differential as a rate of change of the fuel pressure in the common rail with the passage of time with the injection of the fuel, and eliminates a variation in the injection characteristic of the injector. A final target control amount obtained by correcting a basic target control amount based on the target injection characteristic and the injection characteristic is set, and the injection characteristic by the injector is controlled based on the final target control amount. The characteristic is a maximum injection rate, the target injection characteristic is a target maximum injection rate, the basic target control amount is a basic target command pulse output timing to the flow control valve, and the final target control amount is , The final target to the flow rate control valve in which the basic target command pulse output timing is corrected based on the maximum injection rate and the target maximum injection rate. A fuel injection system for an engine which is a command pulse output timing. A common rail for storing fuel delivered by a fuel pump, an injector for injecting the fuel supplied from the common rail through a fuel flow path into an engine combustion chamber, a sensor for detecting an operating state of the engine, and the sensor A controller that sets a target target injection characteristic based on a detection signal from the controller and sets a basic target control amount corresponding to the target injection characteristic in order to execute injection of the fuel by the injector, the injector from the controller In a fuel injection device for an engine provided with an electromagnetic valve that opens and closes the nozzle hole in response to a control signal of
The controller obtains an injection characteristic of the injector based on a differential as a rate of change of the fuel pressure in the common rail with the passage of time with the injection of the fuel, and eliminates a variation in the injection characteristic of the injector. the basic target control amount setting the final target control amount is corrected on the basis of said injection characteristic and the target injection characteristic, which controls the injection characteristics by the injector based on the final target control amount, the injection The characteristic is an injection start time, the target injection characteristic is a target injection start time, the basic target control amount is a basic target command pulse output timing to the solenoid valve, and the final target control amount is The final target to the solenoid valve in which the basic target command pulse output timing is corrected based on the injection start timing and the target injection start timing. A fuel injection system for an engine which is a command pulse output timing. The injection characteristic is the total injection quantity, the target injection characteristic is the target total injection quantity, the basic target control amount is a basic target gross command pulse width to the solenoid valve, the final target control amount it is as defined in claim 9, characterized in that the final target gross command pulse width of the basic target gross command pulse width to the total injection amount and the target total injection amount and the solenoid valve which is corrected based on Engine fuel injection device. The injection characteristic is an initial injection amount, the target injection characteristic is a target initial injection amount, the basic target control amount is a basic target initial command pulse width to the solenoid valve, and the final target control amount is 10. The fuel injection device for an engine according to claim 9 , wherein the basic target initial command pulse width is a final target initial command pulse width obtained by correcting the basic target initial command pulse width based on the initial injection amount and the target initial injection amount . The engine has a plurality of cylinders provided with the injectors, and the correction of the basic target control amount is based on the injection characteristics obtained at the time of the previous fuel injection for each injector provided in the cylinders. The engine fuel injection device according to any one of claims 8 to 11, wherein the fuel injection device is performed based on the above. The engine fuel according to any one of claims 8 to 12, wherein a detection signal of the sensor is converted into a digital signal and then input to the controller via an element for high-speed calculation. Injection device.

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